Modern diagnostic medicine has benefited significantly from radiology. Radiation, such as x-rays, may be used to generate images of internal body structures. In general, radiation is emanated towards a patient's body and absorbed in varying amounts by tissues in the body. An x-ray image is then created based on the relative differences of detected radiation passing through the patients' body.
Surgical navigation guidance can provide a tool for helping the physician perform surgery. One known technique involves tracking position in real-time of a surgical instrument in the patient's anatomy as it is represented by an x-ray image. The virtual representation of the surgical instrument is a three-dimensional object superimposed onto the two-dimensional image of the patient. Thus, the three-dimensional representation appears to be directed into or out of the two-dimensional image of the patient. An exemplary surgical navigation guidance system is disclosed in U.S. application Ser. No. 09/274,972 filed on Mar. 23, 1999 which is assigned to the assignee of the present teachings and incorporated herein by reference.
When an image is acquired, it is acquired from a certain perspective or point-of-view. In the case of a C-arm imaging device, the perspective is determined by the orientation of the C-arm around the patient. Specifically, the perspective is along the line connecting the image source and the image receiver. If the surgeon navigates the surgical instrument from the position of the image receiver, the perspective of the virtual representation of the instrument will match the surgeon's perspective of the actual instrument. However, if the surgeon navigates from the position of the radiation source, the perspective of the virtual representation of the instrument will appear “flipped” from the surgeon's perspective of the actual instrument.
Therefore, it is desirable to provide a surgical navigation system that allows the surgeon to invert or “flip” the three-dimensional perspective of the instrument to match their perspective of the actual instrument.